ISINF(3) | Library Functions Manual | ISINF(3)

# NAME

isinf — test for infinity

# LIBRARY

Standard C Library (libc, -lc)

# SYNOPSIS

#include <math.h>

int
isinf(real-floating x);

# DESCRIPTION

The isinf() macro determines whether its argument x is an infinity (positive or negative). An argument represented in a format wider than its semantic type is converted to its semantic type first. The determination is then based on the type of the argument.

## IEEE 754

It is determined whether the value of x is an infinity.

## VAX

Infinities are not supported.

# RETURN VALUES

The isinf() macro returns a non-zero value if the value of x is an infinity. Otherwise 0 is returned.

# SEE ALSO

fpclassify(3), isfinite(3), isinff(3), isnan(3), isnanf(3), isnormal(3), math(3), signbit(3)

IEEE Standard for Binary Floating-Point Arithmetic, Std 754-1985, ANSI.

# STANDARDS

The isinf() macro conforms to ISO/IEC 9899:1999 (“ISO C99”).

March 5, 2004 | NetBSD 7.2